Remove Color conversion in color.py if they exist in the colour module

[BrorSebastianSjovald]

The current functions that handle color conversion duplicate functionality of existing libraries. According to the enchancement proposal these should be removed. All instances where these functions are used should be replaced by those in the colour-module.

In DarrylGolden's words:

We have many functions for converting between color representations that duplicate the functionality of existing, specialized libraries. Any uses of those should be replaced, probably by methods of Color, and the functions eventually removed.

[BrorSebastianSjovald]

Closed by #10